Tungsten inert gas (TIG) welding is an important arc welding process that uses a non-consumable tungsten electrode and an inert gas for arc shielding that provides very good weld quality and precision welding operation. In the welding process, when the selection of welding materials, joint configuration, welding variables, and level settings of the welding parameters were not suitable and inappropriate, the weld bead does not get optimum weld strength and ductility, which creates damage and broken-down on the welded joint when applying load/pressure. The aim of this research is to present optimum process parameters on attempting to obtain enhanced mechanical properties of the weld joint. In this study, the experimental analysis methodology was used. The experiment was conducted on 5 mm 304L stainless steel and 1.6 mm diameter ER308L filler metal by using argon as shielding and 2.4 mm diameter of tungsten electrode. A flat welding position and butt joint configuration was employed with 60 degree included angles. The selected process parameters were travel speed, welding current, gas flow rate, arc length, and root gap. A mixed Taguchi design L16 orthogonal array was used to optimize process parameters using Minitab 19 software. Taguchi based grey relation analysis method was used with a larger is better quality characteristics. Hardness test, tensile strength, and bending strength tests were the examined mechanical properties on the weld joint. Based on the Taguchi based grey relational analysis, the optimal level setting of travel speed, welding current, gas flow rate, arc length, and root gap was obtained 2.7mm/sec, 160A, 14 lit/min, 3 mm, and 1mm respectively. ANOVA was conducted in order to examine the significant welding process parameters. The analysis result shows that the welding current has the greatest influence followed by travel speed and root gap on weld joint quality with percentage contribution of 81.55%, 8.8%, and 4.99% respectively; whereas, gas flow rate and arc length are insignificant parameters. Five confirmation tests were conducted, and the results show that the average values of the mean grey relational grade 0.863 fall within the 95% confidence level between 0.8493 and 1.0067; accordingly, the experiment is confirmed as acceptable. By using optimal level setting of TIG welding parameters, the maximum hardness, tensile strength and bending strength were obtained 101.38HRB, 1425.8MPa and 1648.6MPa respectively. Keywords: 304L Stainless Steel, TIG welding parameters, Mechanical properties, Grey-based taguchi method, ANOVA,